1. Field of the Invention
The present invention relates to a data entry device having keys which have multiple functions. In particular the present invention relates to a data entry device having relatively few keys, compared to an ordinary or standard keyboard, and in which each key can produce three, four or five characters depending upon how the key is depressed. The data entry device eliminates the need for a shift key or function key which, in a conventional keyboard, must be depressed simultaneously with another key to produce a second function, such as capitalization or a second character.
2. Description of the Prior Art
A standard keyboard has keys corresponding to the 26 letters of the alphabet, numbers 0-9, punctuation, and other various commonly used symbols. Including a shift key, a control key and an alt key, the total number of keys is approximately 50 Most of the keys will produce a second character when depressed simultaneously with the shift key. Similarly, if the alt key or control key are depressed with one of the other keys, character different from the primary character will be produced.
While the standard keyboard is sufficient for normal use at a work station, it does not lend itself to use in hand-held devices, or other situations where a large keyboard would be awkward or inappropriate. For a hand-held device, a data entry device would preferably require only one hand to enter data. Consequently, a requirement of using a shift, control or alt key simultaneously with other keys would be a drawback.
Other arrangement of keyboards exist beside the standard arrangement. For example, U.S. Pat. No. 4,891,777 to Lapeyre is directed to a single hand keyboard array which provides alphanumeric capabilities from twelve keys. The keyboard is intended to be operated using one hand. The system employs virtual keys which are selected by simultaneous action of two or more individual keys. The apparatus decodes the signals produced by activation of the switches to produce the alphanumeric symbol desired.
U.S. Pat. 5,087,910 to Guyot-Sionnest pertains to an electronic keyboard for one-hand operation. The keyboard produces alphanumeric and analog characters upon the activation of one or more finger keys and a thumb key. The finger keys can each assume one of three states, and the thumb key can assume five different states. The keys can thereby, in combination, produce 134 different characters.
Another device is described in U.S. Pat. No. 5,543,818 to Scott which relates to a method and apparatus for entering text using an input device having a small number of keys. A display device, connected to a CPU, displays a character selection menu having sixteen groups of characters. An input device which includes four cursor movement keys and four selection keys to choose a desired character. The four cursor movement keys move the cursor on the display from one character group to another. The four selection keys determine which of four characters in a group is desired.
U.S. Pat. No. 4,680,577 to Straayer et al teaches a multipurpose cursor control keyswitch. The switch has an ordinary function of producing an alphanumeric symbol when depressed vertically, and directs cursor movement when horizontal pressure is applied. The Straayer et al keyswitch is not intended to reduce the number of keys and is not designed to facilitate one hand operation.
A multiple switch assembly including a rockable control plate for selectively actuating multiple microswitches is disclosed in U.S. Pat. No. 5,504,286 to Tsai. The assembly is intended to reduce the number of keys on the keyboard of a portable computer by employing rockable keys which can produce two characters without reducing the size of the keys. The keys can be pressed to either one of two sides corresponding to two different characters. The primary reason for reducing the number of keys is to accommodate a cursor movement device.
U.S. Pat. No. 4,769,516 to Allen relates to a finger operated switching apparatus. The keyboard utilizes keys which can produce three different characters. The keyboard is intended to replace a conventional keyboard and requires two hands for use.
U.S. Pat. No. 5,504,286 to Blauer pertains to a keyboard with elongate keys associated with compact switch mechanisms. The keyboard is intended to be used with both hands and is intended for use in a desk-top configuration. The keyboard has a series of keys which produce two or three outputs depending upon how the keys are depressed.